Rockwell Automation Publication 750-UM002H-EN-P - February 2017 29
Chapter 3
Safe Torque Off Option Module Operation
This chapter provides operation and Stop Category example wiring diagrams
for the PowerFlex® 750-Series Safe Torque Off option module.
Operation
The PowerFlex 750-Series Safe Torque Off option module (see Figure 5)
disables the drive’s output IGBT’s by disconnecting power to the gate control
driver IC or disabling the output of the gate-control driver IC. This helps
prevent the drive’s output power devices from switching in the pattern
necessary to generate AC power to the motor.
The safety option module can be used in combination with other safety devices
to satisfy the requirements of IEC 61508, IEC 61800-5-2 SIL 3,
EN ISO 13849-1 PLe, and Category 3 for Safe Torque Off (STO).
Topic Page
Operation 29
Stop Category Wiring Examples 30
IMPORTANT The safety option module is suitable for performing mechanical work on the
drive system or affected area of a machine only. It does not provide electrical
safety.
The safety option module should not be used as a control for starting and/or
stopping the drive.
IMPORTANT The safety option module does not eliminate dangerous voltages at the
drive output. Input power to the drive must be turned off and safety
procedures followed before performing any electrical work on the drive or
motor. Refer to Remove Power From the Drive System
on page 21 for more
information.
ATTENTION: In the event of the failure of two output IGBTs in the drive,
when the safety option module has controlled the drive outputs to the OFF
state, the drive can provide energy for up to 180° of rotation in a 2-pole
motor before torque production in the motor ceases.
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